The invention relates to bonding of a plastic fixture on a glass container and further a procedure for achieving a permanent bond.
Bondings of a plastic fixture with a glass container are known in a number of designs for various applications. One essential field of application in which such compounds are subject to great demands is the field of glass containers for holding and transporting liquids with very high or fluctuating temperatures, such as coffee or teapots. The plastic fixture of such containers is designed as a pouring element or pouring brim, which surrounds the wall of the glass container in the opening area and is attached to the glass container. As a rule polypropylene is used as a material. The attachment occurs in accordance with a first design mechanically as a rule by means of frictional connection. On the basis of the differing materials of the elements coming into contact with one another—glass container and plastic fixture—and their differing thermal expansion coefficients, this type of attachment frequently results in glass breakage. To solve this problem, the mechanical coupling has been dispensed with and an integral joint between glass container and plastic fixture by means of adhesion has been resorted to. The problematic nature of these bonds however lies in the poor bonding properties of polypropylene, which can be improved by means of a time-consuming and expensive pretreatment of the plastic, but which nevertheless only supplies unsatisfactory results with regard to the strength of the bond under common temperatures of the filling fluids for the glass container of >70° C. and thus represents a safety risk.
Therefore, the object of the invention is based on creating a permanently secure bond of a plastic fixture to a glass container, which is independent from the application and the selected materials for the plastic fixture. The solution should be distinguished by a low production and assembly cost and should be economical. Expensive pretreatments of the plastic are to be avoided.